Relationship of the physicochemical properties of novel ZnO/biochar composites to their efficiencies in the degradation of sulfamethoxazole and methyl orange

• Published in: The Science of the total environment 2020-12, Vol.748, p.141381-141381, Article 141381
• Main Authors: Gonçalves, Mayara Gabriela, da Silva Veiga, Paulo Apolinário, Fornari, Mayara Regina, Peralta-Zamora, Patricio, Mangrich, Antonio Salvio, Silvestri, Siara
• Format: Article
• Language: English
• Subjects: Composite; Methyl orange; Photocatalysis; Sulfamethoxazole; ZnO/biochar
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.141381

Three different composites were produced, based on zinc oxide and biochar (ZnO/biochar), varying the type of biomass (Salvinia molesta: SM; exhausted husk of black wattle: EH; and sugarcane bagasse: SB), with pyrolysis under mild conditions at 350 and 450 °C. Evaluation was made of the capacities of the composites for photocatalytic degradation of sulfamethoxazole antibiotic (SMX) and methyl orange dye (MO). The properties of the prepared composites were influenced by the biomass source, with larger crystallite size (SB), lower band gap energy (SM), higher specific surface area (SB), and larger pore size (SM) resulting in higher photocatalytic efficiency. Good degradation results were obtained using these innovative photocatalysts prepared at low temperatures, when compared to ZnO/biochar materials reported in previous studies. The best degradation capacities were obtained for the composites produced at 450 °C from SB and SM, with 99.3 and 97% degradation of SMX after 45 min, and 90.8 and 88.3% degradation of MO after 120 min, respectively. [Display omitted] •Novel ZnO/biochar composites were produced from Salvinia molesta, sugarcane bagasse, and exhausted black wattle bark.•Composites produced at 450 °C showed higher catalytic activity, due to greater quantities of organic free radicals.•All the ZnO/biochar composites showed lower band gap energy, compared to ZnO.•Degradation efficiencies of 90% for methyl orange and 100% for sulfamethoxazole were achieved.•The SB450 and SM450 composites showed avoidance of ē/h+ recombination during the degradation reactions.